1. Cytogenetic studies of human neoplastic, hematologic, and congenital diseases, with special emphasis on patients with AIDS who develop leukemia, lymphoma, or Kaposi's sarcoma. Specific diseases studies include lymphoma (Burkitt's and non-Burkitt's), non-small cell carcinoma of the lung, rhabdomyosarcoma, renal cell carcinoma, small-cell tumors in childhood, acute lymphocytic leukemia, preleukemia, secondary leukemia, and esophageal cancer. 2. Cytogenetic studies in rhabdomyosarcoma: direct studies of specimens from 12 patients and studies of 8 established cell lines. 3. Localization of genes in normal chromosomes, using in situ hybridization. 4. Cytogenetic and virus integration studies (using in situ hybridization) of human foreskin cell lines infected with human papilloma virus. 5. Fragile sites studies: A. Continuation of in vitro studies of fragile sites in peripheral blood chromosomes from individuals of different ages. B. Studies of fragile sites in the peripheral blood of high risk cancer families, e.g., melanoma and dysplastic nevi syndrome.